Form Milling Cutter Tooth Geometry for Titanium Alloy Machining

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Solution Overview

Problem

Current manufacturing methods for fir-tree and bulbous root form milling cutters are limited by the number of teeth that can be produced due to the diameter of the grinding wheel, restricting cutting efficiency and requiring extensive broaching operations, which are costly and time-consuming.

Innovation Solution

A method involving the grinding of a blank with a grinding wheel to generate a flat clearance angle and variable tooth depth, allowing for a higher tooth and flute density by controlling the shape and dimensions of each tooth, enabling the production of form milling cutters with up to 10 times more teeth for a given diameter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the diameter of the grinding wheel is increased to produce fewer teeth with adequate clearance, then the clearance angle can be maintained, but the number of teeth that can be produced is limited

Engineering Contradiction:
Improveclearance angleVSAvoidnumber of teeth
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The invention changes the fundamental parameter of clearance generation from arc-based (dependent on grinding wheel diameter) to linear path-based (independent of grinding wheel diameter). By using the equation X = [(R tan Θ) cos Θ] cos Θ to calculate tooth width based on linear movement distance, the system decouples the number of teeth from grinding wheel diameter constraints, enabling production of cutters with 10-20 times more teeth while maintaining adequate clearance angles.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the number of teeth on the milling cutter is increased to improve cutting efficiency, then the metal removal rate increases, but the tooth geometry becomes too complex to manufacture with conventional grinding methods

Engineering Contradiction:
Improvemetal removal rateVSAvoidtooth geometry fabrication
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The invention segments the tooth geometry definition into distinct calculable parameters: tooth width X derived from linear movement distance and clearance angle Θ, and variable depth Y at different locations around the cutter. This segmentation allows complex multi-tooth geometries to be manufactured by systematically applying these formulas rather than relying on conventional arc-based grinding methods, enabling production of cutters with 10-20 teeth or more.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from two-dimensional arc-based clearance generation to three-dimensional linear path-based clearance generation. By defining clearance through linear movement distance along the grinding wheel path rather than through arc rotation, the system adds a dimensional approach that enables precise control of tooth geometry for high-density tooth configurations that were previously unmanufacturable.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If conventional broaching operations are used to machine roots of desired profile, then the desired profile can be achieved, but extensive broaching operations from roughing to finishing are required involving substantial capital costs and machining time

Engineering Contradiction:
Improveroot profile accuracyVSAvoidmachining time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The invention performs preliminary action by pre-forming the complete root profile geometry directly on the milling cutter teeth during manufacturing. By calculating and generating the exact variable depth Y at each location around the cutter perimeter, the cutter is pre-configured to machine the final root profile in a single operation, eliminating the need for subsequent broaching operations and enabling direct production of precision root profiles.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2480364B1Form milling cutter for the machining of titanium alloys etc
Publication Date: 2014.01.15 ROLLS ROYCE PLC
  • EP2480364B1 patent drawingFigure 1A
  • EP2480364B1 patent drawingFigure 1B~1C
  • EP2480364B1 patent drawingFigure 2A~2B

AI summary

A method of manufacturing a multi-tooth fir-tree or bulbous form milling cutter, by the grinding of a blank with a grinding wheel, wherein, a flat clearance angle T of between 0° and 20° is generated on each tooth (13) by the path (14) of the grinding wheel (10), with each tooth (13) having a width (X) from tip to point of maximum clearance (see Figure 5), calculated as follows:- X = {[(RtanT)cosT]cosT}±0.25% (being calculation (A)) where R = radius of cutter, and where T = clearance angle measured from a tangent to the tooth tip, and furthermore, wherein, each tooth (13) has a variable depth (Y) around the cutter, calculated as follows:- Y = {[pD] / [180/T]} 0.5 ±0.2. (being calculation (B)) where D = maximum diameter of the form at any given point along the form. The invention also includes fir tree and bulbous milling cutters produced by the above defined method.